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Development of Thyroid Gland• It is developed from endodermal cells of floor of
pharynx (area of developing tongue).• It begins a diverticulum at dorsum of tongue
between tuberculum impar and hypobranchial eminence.
• Elongation of thyroid diverticulum to form thyro-glossal duct. It elongates downwards infront hyoid and thyroid cartilage where it ends by dividing into 2 parts.
• Ultimobranchial body gives parafollicular cells to thyroid gland. Dr. Sherif
Fahmy
Dr. Sherif Fahmy
Foramen cecum
Thyroglossal diverticulum
Developing anterior 2/3 of tongue
Dr. Sherif Fahmy
Thyroglossal duct
Thyroid gland
Developing anterior 2/3 of tongue
Dr. Sherif Fahmy
Foramen cecum
Degenerating thyro-glossal duct
Hyoid bone
Thyroid cartilage
Levator glandulae thyroidaePyramidal lobe Lobe of
thyroid gland
Fate of Thyro-glossal Duct• Upper end of the duct remains as foramen cecum
on dorsum of tongue.• The duct degenerates from foramen cecum and
hyoid bone.• The duct from the hyoid to divisions of the duct
form levator glandulae thyroidae and may be pyramidal lobe.
• Divisions of the duct form lobes of thyroid gland with isthmus inbetween.
• Ultimobranchial body forms parafollicular cells of the gland.
Congenital Anomalies • Thyroid agenesis: Failure of its formation.• Lingual thyroid: Failure of thyroid descend.• Aberrant thyroid (Retrosternal goiter): over-
descend of thyroid gland in the thorax.• Thyroglossal cyst: It is persistence of a part of
the thyroglossal duct.• Thyroglossal fistula: Thyroglossal duct opens
to skin.
Dr. Sherif Fahmy
Dr. Sherif Fahmy
Dr. Sherif Fahmy
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